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Three flying agencies are Indian Air Force, Air Survey Company, Kolkata and National Remote Sensing Agency, Hyderabad have been officially authorised to take aerial photographs.
1. Time freezing ability.
2. Broadcasting sensitibility.
3. Three dimensional perspective.
4. Improved vantage point.
1. Vertical photographs
2. Low oblique
3. High oblique.
1. Photogrammetry : It refers to the science and technology of making reliable measurements from aerial photographs.
2. Image Interpretation : It is an art of identifying images of objects and judging their relative significance.
1. By establishing relationship between photo distance and ground distance : In this method if additional information like ground distance of two identifiable points in an aerial photograph is available it is simple to work out the scale of a vertical photograph.
2. By establishing relationship between photo distance and map distance : If a reliable map is available for the area shown on an aerial photograph it can be used to determine the photo scale.
3. By establishing relationship between focal length and flying height of the Aircraft
We can determine the photo scale provided the information about the focal length of camera and the flying height of the aircraft are known.
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Aerial Photograph |
Map |
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• It is a central projection. |
• It is an orthogonal projection. |
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• The scale of the photograph is not uniform. |
• The scale of the map is uniform throughout the map extent. |
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• Enlargement/reduction does not change the contents of the photographs and can easily be carried out. |
• Enlargement/reduction of the maps involves redrawing it afresh. |
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• Aerial photography holds good for inaccessible and inhospitable areas. |
• The mapping of inaccessible and inhospitable areas is very difficult and sometimes it becomes impossible. |
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